1. Field of the Invention
The present invention relates generally to liquid crystal display devices for use in personal computers and workstations or else and, more particularly, to effective techniques for application to spacers.
2. Description of the Related Art
Liquid crystal display devices are becoming increasingly well known and commercially available for use as monitor units of modern digital equipment including, but not limited to, laptop personal computers and desktop computers. Today, liquid crystal display modules of the super twisted nematic (STN) or thin-film transistor (TFF) type are widely employed as display devices of notebook computers.
These liquid crystal display modules are generally constituted from a liquid crystal display panel having semiconductor chips (semiconductor integrated circuit devices making up drain drivers or gate drivers) disposed around the peripheral portions thereof, a back-light unit for illumination of the liquid crystal display panel, and a frame having a display window and covering the liquid crystal display panel and the backlight unit.
Additionally such architecture has been recited, for example, in Japanese Patent Publication No.19474/1985 and also in Published Japanese Utility Model Laid-Open No.22780/1992.
In such products, the liquid crystal display device is mounted as what is called the liquid crystal display module including in combination its liquid crystal display panel and light source. One typical form of it is disclosed, for example, in Japanese Patent Laid-Open Nos.264991/1993 and 218914/1995. Typically a chip spacer for protection of the semiconductor chips is provided between the frame and liquid crystal display panel.
And this chip spacer is tightly secured by adhesion to both the frame and one substrate of the liquid crystal display panel (in the case of TFT liquid crystal display module, a glass substrate on the TFT substrate side).
However, in prior known liquid crystal display modules, the one substrate could break (crack) from time to time during assembly processes.
The present invention has been made to solve the problem faced with said prior art, and a primary objective of this invention is to provide a technique for preventing occurrence of substrate cracking in a liquid crystal display device during assembly processes, thereby improving the quality thereof.
The above and other objects and new features of the instant invention will become apparent from the disclosure of the specification along with its accompanying drawings enclosed herewith.
In products such as monitor units of laptop personal computers and desktop personal computers, a variety of types of commercial products are becoming available in recent years.
The inventors as named herein have considered about the cause of the cracking of one substrate of the liquid crystal display element (liquid crystal display panel) during assembly of a liquid crystal display module to find that one major problem concerns the position of an adhesive layer as provided at the spacer.
More specifically, in prior art liquid crystal display modules, the adhesive layer is provided on the entire surface of the spacer. This spacer""s adhesive layer is provided in such a way as to also cover a wiring substrate or board which is electrically and/or mechanically connected to more than one terminal section being provided at the periphery of the above-noted one substrate.
It has been found that due to this arrangement, a compressive force will first be applied to a region in which the one substrate""s wiring board is formed when attaching a frame member during assembly of a liquid crystal display module, and the terminate end portion of such one substrate is inherently weak in physical strength than its remaining regions other than the end portion, thus resulting in occurrence of substrate cracking in this region first.
The present invention has been made in view of the above technical background. Some representative principles of the invention as disclosed herein will be explained in brief below.
More specifically the present invention provides a liquid crystal display device which comprises a liquid crystal display device comprising a liquid crystal display element, a frame member having a display window permitting exposure of a display plane of said liquid crystal display element and covering said liquid crystal display element, and a spacer provided between said frame member and a periphery of a first principal surface of one substrate of said pair of substrates facing said liquid crystal, featured in that said spacer is provided with an adhesive layer at specified part of said first principal surface of said one substrate closer to said liquid crystal than a central portion of the length in the direction crossing one side thereof.
Another feature of the present invention is that said spacer is provided with the adhesive layer at part of said first principal surface of said one substrate closer to said liquid crystal than the central portion of the length at right angles to the one side of said first principal surface.
The present invention also provides a liquid crystal display device comprising a liquid crystal display element having a semiconductor integrated circuit device as provided on a periphery of the liquid crystal side surface of one of the substrates, a frame member having a display window exposing a display plane of said liquid crystal display element and covering said liquid crystal display element, and a spacer provided between said frame member and a periphery of the liquid crystal side surface of said one of the substrates, characterized in that one side (lateral face) of said spacer adjacent to said liquid crystal display element is formed into an even shape (shaped so that the one side protruded toward the liquid crystal display element at plurality of portions thereof), said semiconductor integrated circuit device is disposed along a concave portion thereof, and an adhesive is provided on a surface of a convex portion thereof opposing the liquid crystal side surface of said one substrate. The aforementioned convex portion is defined as a portion of the spacer where the one side is protruded toward the liquid crystal display element, and the aforementioned concave portion is defined as a portion of the spacer (other than the concave portion) where the one side is not protruded toward the liquid crystal display element. In the aforementioned spacer, a plurality of the concave portions and a plurality of the convex portions are arranged alternately along an extension direction of the spacer, and thus the spacer looks like e.g. a profile of rack rail. The aforementioned liquid crystal side surface of one of the substrates is defined as a main surface at a liquid crystal layer side of one of a pair of substrates between which the liquid crystal layer is interposed. The aforementioned semiconductor integrated circuit device is provided on a area of the liquid crystal side being surrounded by one of the aforementioned concave portions and at least one of the aforementioned convex portions (as if it were inserted into a notch formed at the one side of the spacer according to the concave portion). More concretely, the convex portion of the spacer protrudes toward the effective display region of the liquid crystal display element. Therefore, if the spacer is arranged on a area at the periphery of one substrate of the pair of substrates where another substrate of the pair of substrates is not superposed over the one substrate, the convex portion of the spacer protrudes toward an edge of the another substrate, and other portion of the spacer than the convex portion becomes a concave portion with respect to the another substrate.
Another feature of the present invention is that said one substrate has a terminal section at a peripheral edge portion and also has a wiring board as electrically and/or mechanically connected to said terminal section, and that the adhesive layer of said spacer is provided in a region other than a region to be provided with said wiring board.
With the above-stated means, since the position of the adhesive layer to be provided at the spacer is designed so that this adhesive layer is provided at a specified peripheral position of one substrate which is spaced apart by a predetermined distance from one edge portion, it is possible to prevent occurrence of cracking of the substrate of the liquid crystal display element, which in turn makes it possible to improve the product quality.
The above-stated features of the instant invention are also implementable with the following forms.
One example of such forms is that in a liquid crystal display device comprising a liquid crystal display element having a pair of substrate and a layer of liquid crystal interposed between said pair of substrate, a frame member having a first portion opposing a display plane side of said liquid crystal display element and an opening as formed at the first portion for permitting exposure of the display plane, and a spacer being disposed between one substrate of said pair of substrates and said first portion of said frame member and extending along a boundary between said first portion and said opening, an adhesive portion for adhesion between said spacer and the one substrate of said pair of substrates is formed in such a manner that it is spaced apart from an end portion of the one substrate of said pair of substrates extending along said boundary (i.e., line segment whereat the first portion of said frame member is in contact with the opening).
The one substrate of the pair of substrates as used herein may be a display plane side (so-called top surface side) substrate or, alternatively, a back surface side substrate of the liquid crystal display device.
In either case, by forming said adhesive section so that it is distant from the edge portion of the one substrate of said pair of substrates, a gap space extending along this edge portion is formed between said spacer and the one substrate of said pair of substrate.
With such an arrangement, a demonstrable advantage of the invention obtainable in addition to the above-noted effect and advantage is its ability to allow the spacer resiliently deformable into said gap to absorb mechanical forces being applied to the substrate(s) via said frame member from outside of said liquid crystal display device to thereby preclude any possible destruction of the liquid crystal display element otherwise occurring due to such externally applied mechanical forces.
It should be noted that the frame is not always required to cover the entirety of the peripheral edges of the pair of substrates. This frame may be arranged to cover at least part whereat said spacer is to be provided.
In a view point of obtaining these effects, said spacer is preferably designed to have its elasticity or flexibility greater than that of the one substrate of said pair of substrates. One desired example is that the spacer is machined using polyethylene terephthalate. Another example is that it is machined to have a multi-layer of a plurality of films (including more than one synthetic resin film made of polyethylene terephthalate or other similar suitable material, and a metallic film or films).
In case said spacer is laid out so that its edge portion opposing one side of the other substrate of said pair of substrates is spaced apart from one side of the other substrate of this pair of substrates, any forces due to the spacer""s bending deformation will no longer be applied to this other substrate of the pair of substrates, thus enabling reduction of display irregularities otherwise taking place at the liquid crystal display element.
A still another example is that in a liquid crystal display device comprising a liquid crystal display element having a first substrate (also called the lower side substrate) with a first principal surface, a second substrate (also called upper side substrate) having a second principal surface narrower than the first principal surface and being disposed to let this second principal surface oppose the first principal surface, and a layer of liquid crystal material interposed between the first principal surface and the second principal surface, a frame member having a first portion opposing a first region (also called picture frame-like region) of said first principal surface which does not oppose said second principal surface and an opening as formed to oppose an upper surface of said second substrate, and a spacer being disposed between said first region of said first principal surface and said first portion of said frame member and extending along an end portion of the first substrate adjacent to the first region, an adhesive portion for adhering said spacer to said first region of said first substrate is formed so that it is distant from an end portion adjacent to said first region of said first substrate.
For the purpose of automation of assembly processes, it is preferable that said spacer be formed to have a band-like shape having a surface along said first region of said first substrate.
In addition, an end portion of said spacer facing an end portion of said second substrate adjacent to said first region of said first substrate is distant from the end portion of said second substrate adjacent to said first region of said first substrate. This arrangement is preferable for suppression of display irregularities of the liquid crystal display device as stated previously.
In case a driver device for driving said liquid crystal display element is built in said first region of said first substrate, said spacer is provided with a plurality of projection portions which are projected toward the end portion of said second substrate adjacent to said first region of said first substrate while disposing said driver device so that it is put between a pair of certain ones of the plurality of projections. With this arrangement it is possible to make thinner the liquid crystal display device without spoiling the advantages of the present invention stated supra.
At this time it is preferable that said adhesive section be formed only at either one of said plurality of projections.
The above-stated principal features of the present invention will also be described in more specific preferred forms for reduction to practice as will be set forth later in the description. Any members and structures as disclosed therein may be replaced by any other alternative ones without suffering from any appreciable hindrance to the practical implementation of the present invention.
These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings.